Abstract: Tube inversion including free deformation under conical die is an advanced forming process for manufacturing complicated thin-walled parts with high strength/weight ratio, high efficiency, and good flexibility for size changing. However, the successful reality of forming process, the change of deforming mode and shape and size of part formed are mainly on the die angle. Based on the analysis of the forming process, the model of rigid-plastic FEM (finite element method) is established and a numerical simulation system is developed. The effect of die angle on the tube inversion forming process is investigated with the code developed. The results of the effect of half die angle on shape of free deformation zone and on deforming load are obtained. There is an optimal die angle (about 75 deg), which makes the forming load minimum.

Key words: Tube inversion under conical die, Rigid-plastic FEM, Die angle, Free deformation